Variable N1 Scale Resolution for Aircraft Thrust Setting
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Solution Overview
Problem
Existing systems for displaying turbofan engine fan speed (N1) as a thrust setting parameter face challenges due to its non-linear relationship with thrust, resulting in low resolution at high thrust levels, making it difficult for pilots to accurately determine and set target thrust values.
Innovation Solution
Implementing a variable nonlinear scale and color cues for the N1 display to enhance resolution and visual feedback, allowing pilots to discern if the current thrust is within a specified tolerance, thereby improving the accuracy and sensitivity of thrust setting at high thrust levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear N1 scale is used for displaying fan speed as thrust setting parameter, then the display is simple and easy to understand, but the resolution at high thrust levels is insufficient making it difficult for pilots to accurately determine target thrust values
Solution Approach 1:
The patent applies local quality by implementing a non-uniform scale where different regions of the dial have different densities of tick marks. Specifically, the scale has higher density (more tick marks per degree) in the upper thrust region (e.g., 80-100% N1) where resolution is needed for accurate thrust setting, and lower density in the lower thrust region. This allows the display to provide high measurement precision where required while maintaining overall simplicity.
Solution Approach 2:
The patent implements dynamics by making the scale adaptive to different operating conditions. The display system can dynamically adjust the scale characteristics based on the current thrust regime, providing enhanced resolution in the takeoff thrust region when needed for accurate thrust setting, while maintaining a simpler appearance during other phases of flight. This dynamic adaptation resolves the contradiction between precision and simplicity.
2Adaptability or versatility
If N1 is used as both tachometer indication and thrust setting parameter, then the number of displays is reduced, but the non-linear relationship between N1 and thrust causes loss of resolution at upper end of scale
Solution Approach 1:
The patent resolves this contradiction by applying local quality to the scale design, where the density of scale markings varies by region. In the thrust setting region (upper N1 values where thrust is most critical), the scale has increased density of tick marks to provide fine resolution for accurate thrust determination. In other regions, the scale maintains standard density. This allows the single N1 display to fulfill both tachometer and thrust setting functions with appropriate precision in each regime.
Solution Approach 2:
The patent applies parameter changes by modifying the scale transformation function based on the operating regime. The display system changes the mapping between N1 value and dial position in different regions, using a non-linear transformation that compresses the lower N1 range and expands the upper N1 range. This parameter change allows the same display to provide adequate resolution for both low-speed tachometer indication and high-speed thrust setting.
3Ease of operation
If a conventional uniform scale is used for N1 display, then the display structure is simple, but pilots cannot easily detect or set small thrust increments at high thrust
Solution Approach 1:
The patent improves ease of operation for detecting small thrust increments by applying local quality to the scale markings. In the critical high-thrust region where small increments matter most (e.g., during takeoff), the scale incorporates closely spaced tick marks that allow pilots to visually detect and set small thrust changes. This localized enhancement of marking density makes the display easier to use for thrust setting without requiring complete redesign of the entire scale structure.
Solution Approach 2:
The patent applies segmentation by dividing the N1 display scale into distinct zones with different characteristics. The scale is segmented into a low-thrust region with standard marking density and a high-thrust region with enhanced marking density. This segmentation allows each zone to be optimized for its specific function, making it easier for pilots to detect and set small thrust increments in the high-thrust zone while maintaining overall display simplicity.
Data Source
Figure 1A
Figure 1B~2
Figure 3A~3B
AI summary
Systems and methods for displaying N1 speed on a flight deck display in a manner that provides increased resolution at the upper end of the operating range. This is accomplished by a variable scale(s) which improves the functionality of the N1 gauge (serving as an indication of thrust) in the desired region. Also, there is visual indication to provide pilots the ability to discern if the current thrust is within a specific tolerance to the desired value within the takeoff region. This additional indication is based on color changes associated with the N1 display structure.